Pre-stack seismic inversion seems to be the main technique for reservoir fluid identification; nevertheless, there exist problems such as petrophysical weakness and multiple solutions in its application to investigating geological features of the specific study area. In order to improve the precision of seismic identification of fluid, the author carried out studies of typical reservoirs in such aspects as petrophysical basis and prestack seismic inversion. According to petrophysical data of channel sand tested in the laboratory, the influence of pore fluid and lithology on petrophysical elastic parameters were analyzed. Based on elastic impedance equation, the author obtained the sensitive parameters to the reservoir fluid by means of direct inversion of elastic parameters. Pre-stack seismic inversion was used for fluid identification of shallow layer channel sand reservoir in KD area. The results achieved by the authors show that seismic identification accuracy of fluid has been improved, and a good geological effect has been acquired.